1. Field of the Invention
The present invention relates to a tool for use in installing or removing stud bolts.
2. Description of the Prior Art
Threaded stud bolts are used in a variety of applications. Typically, the stud bolts, designated generally as B, are installed in an internally threaded counter bore or blind bore A as shown in FIGS. 1 and 2. The stud bolts B are threaded along their entire length and have no surfaces for utilizing a wrench to rotate the stud bolt B and thereby threadably engage the stud bolt B with the threaded blind bore A.
FIGS. 1 and 2 disclose two known methods for screwing a stud bolt B into the threaded blind bore A. FIG. 1 illustrates one method in which a box nut 10 is screwed on top of the stud bolt B and a torque wrench (not shown) engages the box nut 10 to rotate it together with the stud bolt B. In FIG. 2, two nuts 12 and 14 are screwed onto the stud bolt B and the nut 14 is rotated so as to tighten the nut 14 against the nut 12 which interlocks the two nuts 12, 14. The nut 14 is then rotated with a torque wrench which also rotates the stud bolt B. In either of the methods shown in FIGS. 1 and 2, it is necessary to apply a force substantially equal to the force required to tighten the box nut 10 to the stud bolt B or the nuts 12, 14 to the stud bolt B in order to loosen and remove the nuts. Removing the cap nut 10 requires use of a torque wrench to loosen the cap nut 10 from the end of the stud bolt B without loosening the stud bolt B from the blind bore A. The stud bolt B cannot be gripped by the threads for fear of damaging the threads. In FIG. 2, the flat side surfaces 16 of the two nuts 12, 14 must be aligned at high torque to enable use of an impact wrench and socket. If an impact wrench and socket is used to loosen the nut 14, the operator's safety will be jeopardized. Thus, this second method typically requires a two tool operation in which the lower nut 12 is held with a wrench while the upper nut 14 is reversibly rotated to free the interlocked nuts. Oftentimes, it is extremely difficult to free the interlocked nuts 12, 14 and it is required to be performed in dangerous environments, as for example, from catwalks, scaffolding, etc. In such circumstances, the sudden breaking loose of one nut under high torque could throw the operator off balance causing the operator to fall from scaffolding, etc.
The second method of using two nuts 12, 14 may also be used to remove the stud bolt B. In the removal operation, a torque wrench is applied to the lower nut 12 and torque is applied in the appropriate direction. Typically, the flat surfaces 16 of the nuts 12 and 14 are not aligned with the nuts are interlocked. Thus, since this is generally the case, in impact wrench with socket cannot be used to rotate the lower nut 12 when removing the stud bolt B. Once the stud bolt B has been removed, a two tool operation is again required to remove the interlocked nuts 12, 14. The stud bolt B is not anchored at this point and removing the nuts 12, 14 is a dangerous operation. One alternative is to take the removed stud bolt B with the interlocked nuts 12, 14 to the machine shop and place one nut in a vise to hold that nut stationary while the second nut may be reversibly rotated with a wrench. However, oftentimes a vise is not available in the field to break loose or free the interlocked nuts 12, 14.
U.S. Pat. No. 4,977,799 discloses a clamping tool for use with a stud bolt. The clamping tool includes a torque transmission mechanism such that the torque necessary to loosen the clamping tool to detach it from the stud bolt tightened in position is much smaller than the torque necessary to tighten the stud bolt. This clamping tool is a complex tool which is expensive to fabricate and which cannot be used to remove a tightened stud bolt from a blind bore.
It is highly desirable to have a tool for stud bolt removal and installation operations which is of simple construction, low cost manufacture, and which is readily mountable to the stud bolt for operation or dismountable from the stud bolt after operation by a single operator in the field with safety.